Electric braking device and manufacturing method thereof

Abstract

To improve workability of component assembly when an electric brake device is manufactured.SOLUTION: A backing plate is formed divided into a sub plate 39 and a plate body 40. A wheel cylinder 14 and an electric motor 21 are respectively assembled to a front surface of the sub plate 39 and a rear surface. Then, the sub plate 39 is fixed to the plate body 40 to assemble the wheel cylinder 14 and the electric motor 21 to the backing plate.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a drum-type electric braking device that generates braking force on a wheel, and a method for manufacturing the same. [Background technology]

[0002] Patent Document 1 describes a known drum-type electric braking device in which a wheel cylinder attached to a backing plate is driven by an electric actuator attached to the backing plate to generate braking force on the wheel. The wheel cylinder is housed in a housing together with a reduction mechanism and a linear motion conversion mechanism.

[0003] In such conventional electric braking devices, the wheel cylinder and the electric actuator are assembled to the backing plate in the following procedure. In the following description, the surface of the backing plate on which the wheel cylinder is located will be referred to as the first surface of the backing plate, and the surface on which the electric actuator is located will be referred to as the second surface of the backing plate. During the assembly, first, the housing is fixed to the first surface of the backing plate with a portion of the housing protruding toward the second surface through an opening formed in the backing plate. Then, the electric actuator is fixed to the portion of the housing protruding toward the second surface, thereby assembling the wheel cylinder and the electric actuator to the backing plate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6557239 Summary of the Invention [Problem to be solved by the invention]

[0005] In the conventional electric braking device described above, when assembling the wheel cylinder and the electric actuator, it is necessary to fix the components on both the first and second surfaces of the backing plate, which is large and difficult to handle, making the assembly of the components during manufacturing cumbersome. [Means for solving the problem]

[0006] The electric braking device that solves the above problem is a drum-type electric braking device in which a wheel cylinder and an electric actuator are respectively mounted on a backing plate, and the electric actuator drives the wheel cylinder to generate braking force on the wheel. The backing plate in this electric braking device is configured by mounting a sub-plate that forms the remaining part of the backing plate to a plate main body that forms part of the backing plate. The wheel cylinder is mounted on a first surface side of the sub-plate, and the electric actuator is mounted on a second surface side that is the back side of the first surface side.

[0007] In the above electric braking device, a sub-plate is assembled to the plate body. Furthermore, a wheel cylinder is assembled to the first surface side of the sub-plate, and an electric actuator is assembled to the second surface side. Therefore, it is possible to fix the sub-plate to the plate body while the wheel cylinder and the electric actuator remain fixed. Therefore, in the above electric braking device, it is possible to assemble the wheel cylinder and the electric actuator together to the backing plate during manufacturing. Therefore, with the above electric braking device, it is possible to improve the workability of assembling parts during manufacturing.

[0008] A manufacturing method for an electric braking device that solves the above-mentioned problems relates to the manufacture of a drum-type electric braking device that includes a wheel cylinder and an electric actuator, each of which is mounted on a backing plate, and in which the electric actuator generates a braking force on a wheel by driving the wheel cylinder. The manufacturing method includes a first step including a step of assembling the wheel cylinder to a first surface of a sub-plate that constitutes part of the backing plate, and a step of assembling the electric actuator to a second surface that is the reverse side of the first surface, and a second step of assembling the sub-plate, to which the wheel cylinder and electric actuator have been mounted in the first step, to a plate main body that constitutes the remaining part of the backing plate.

[0009] In the above manufacturing method, the wheel cylinder and electric actuator are pre-assembled on a sub-plate, which is fixed to the plate body, so that the wheel cylinder and electric actuator are respectively assembled on different surfaces of the backing plate. Since the wheel cylinder and electric actuator can be assembled to the backing plate all at once, the workability of assembling parts during manufacturing is improved. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a plan view of an electric braking device according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view of a drive unit of the electric braking device. [Figure 3] 10 is a view showing a state in which a drive unit is assembled to a backing plate in the electric braking device, as viewed from the front side of the backing plate. FIG. [Figure 4] FIG. 10 is a side view of the backing plate in the assembled state. [Figure 5] FIG. 10 is a plan view of a plate body of an electric braking device according to a second embodiment. [Figure 6] FIG. 2 is a plan view of a drive unit of the electric braking device. [Figure 7] 10 is a side view of the backing plate showing the state in which the drive unit is assembled to the backing plate in the electric braking device. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] (First embodiment) An electric braking device and a manufacturing method thereof according to a first embodiment will be described below with reference to Figures 1 to 4. The electric braking device 10 of this embodiment is a drum-type braking device that electrically generates braking force on a wheel.

[0012] <Configuration of the electric braking device 10> First, the configuration of an electric braking device 10 will be described with reference to Fig. 1. As shown in Fig. 1, the electric braking device 10 includes a brake drum 11 and a backing plate 12. The brake drum 11 is fixed to the axle so as to rotate integrally with the wheel when the electric braking device 10 is mounted on a vehicle. Furthermore, the backing plate 12 is fixed to the vehicle body when the electric braking device 10 is mounted on a vehicle.

[0013] The backing plate 12 is a ring-shaped metal plate with an axle hole 13 formed in the center for passing an axle therethrough. In the following description, when the electric braking device 10 is installed on a vehicle, the side of the backing plate 12 on which the brake drum 11 is located will be referred to as the front side of the backing plate 12, and the opposite side will be referred to as the back side of the backing plate 12. A wheel cylinder 14 is installed on the front surface of the backing plate 12. An anchor member 15 is fixed to the front surface of the backing plate 12 at a portion where the axle hole 13 is located between the wheel cylinder 14 and the backing plate 12.

[0014] The electric braking device 10 includes a pair of brake shoes 16, 17 and a drive unit 20. The brake shoes 16, 17 have an arc-shaped outer peripheral surface that conforms to the shape of the inner peripheral surface of the brake drum 11. Friction materials 18 are attached to the outer peripheral surfaces of the brake shoes 16, 17. One end of each of the brake shoes 16, 17 is engaged with a wheel cylinder 14. The other ends of each of the brake shoes 16, 17 are rotatably supported by an anchor member 15. When the brake shoes 16, 17 rotate so that the distance between the ends engaged with the wheel cylinder 14 increases, the friction materials 18 are pressed against the inner peripheral surface of the brake drum 11. This pressure generates friction between the inner peripheral surface of the brake drum 11 and the friction materials 18, which in turn generates a braking force on the wheel. A return spring 19 is stretched between the two brake shoes 16, 17. The brake shoes 16, 17 are biased by the return spring 19 in a direction in which the friction material 18 moves away from the inner peripheral surface of the brake drum 11. A drive unit 20 drives the brake shoes 16, 17.

[0015] <Configuration and Operation of Driving Unit 20> Next, the configuration of the drive unit 20 will be described with reference to Figure 2. The drive unit 20 includes the wheel cylinder 14, an electric motor 21, a controller 22, and a housing 23. The electric motor 21 is an electric actuator that generates power in response to power supply. The controller 22 is an electronic control device that controls the electric motor 21 to adjust the braking force generated on the wheel. The controller 22 has an electric circuit equipped with a microprocessor and memory, and a drive circuit for the electric motor 21. The housing 23 is a casing that houses the wheel cylinder 14 and a mechanism for transmitting power from the electric motor 21 to the wheel cylinder 14.

[0016] Four gears are arranged inside the housing 23: a first small diameter gear 30, a first large diameter gear 31, a second small diameter gear 32, and a second large diameter gear 33. The first small diameter gear 30 is connected to a rotary shaft 29 of the electric motor 21 so as to rotate integrally therewith. The first small diameter gear 30 is meshed with a first large diameter gear 31, which has a greater number of gear teeth than the first small diameter gear 30. The first large diameter gear 31 is connected to a second small diameter gear 32 so as to rotate integrally therewith. The second small diameter gear 32 is meshed with a second large diameter gear 33, which has a greater number of gear teeth than the second small diameter gear 32. The first small diameter gear 30, the first large diameter gear 31, the second small diameter gear 32, and the second large diameter gear 33 reduce the rotation speed of the electric motor 21 and transmit it to the wheel cylinder 14.

[0017] The wheel cylinder 14 includes a cylinder 24 formed inside a housing 23, and a first piston 25 and a second piston 26 disposed inside the cylinder 24. The first piston 25 has a pressing portion 27 that protrudes outside the housing 23 and engages with one end of the brake shoe 16. The second piston 26 has a pressing portion 28 that protrudes outside the housing 23 and engages with one end of the other brake shoe 17. A return spring 19 stretched across both brake shoes 16, 17 applies pressure to these pressing portions 27, 28 in the direction that reduces the amount of protrusion from the housing 23. This pressure causes the first piston 25 to abut against the end of the screw shaft 35. The first piston 25 and the second piston 26 are prevented from rotating through engagement with the brake shoes 16, 17, etc.

[0018] A second large-diameter gear 33 is disposed in the cylinder 24 between the first piston 25 and the second piston 26. An internal spline 34 extending in the axial direction is formed on the inner periphery of the second large-diameter gear 33. A threaded shaft 35 is disposed inside the cylinder 24 and inserted through the second large-diameter gear 33. The threaded shaft 35 has an external spline 36 extending in the axial direction. The threaded shaft 35 rotates integrally with the second large-diameter gear 33 through engagement of the internal spline 34 with the external spline 36, while being axially movably connected to the second large-diameter gear 33. The threaded shaft 35 has, at its end on the second piston 26 side, a male threaded portion 37 that meshes with a female threaded portion 38 formed on the inner periphery of the second piston 26. As described above, the wheel cylinder 14 is composed of the second large-diameter gear 33, the first piston 25, the second piston 26, and the threaded shaft 35 disposed in the cylinder 24, and the portion of the housing 23 in which the cylinder 24 is formed.

[0019] The rotation of the electric motor 21 decelerated through the first small-diameter gear 30, the first large-diameter gear 31, and the second small-diameter gear 32 is transmitted to the second large-diameter gear 33 of the drive unit 20 configured as described above. When the second large-diameter gear 33 rotates, the screw shaft 35 engaged through the internal tooth spline 34 and the external tooth spline 36 rotates. A male screw portion 37 that meshes with the female screw portion 38 of the second piston 26 is formed on the screw shaft 35. On the other hand, the second piston 26 is prevented from rotating. Therefore, the rotational movement of the screw shaft 35 is converted into a linear movement of the second piston 26 with respect to the screw shaft 35. Then, according to the linear movement of the second piston 26 with respect to the screw shaft 35, the distance between the first piston 25 and the second piston 26 changes. When the distance between the first piston 25 and the second piston 26 increases, pressure is applied to the brake shoes 16 and 17 through the pressing portions 27 and 28, and the friction material 18 provided on their outer peripheral surfaces is pressed against the inner peripheral surface of the brake drum 11. Then, a braking force is generated on the wheel due to the friction between the friction material 18 and the inner peripheral surface of the brake drum 11. On the other hand, when the distance between the first piston 25 and the second piston 26 decreases, the pressing force of the friction material 18 against the inner peripheral surface of the brake drum 11 decreases, and the braking force of the wheel decreases. In the following description, the rotational direction of the electric motor 21 on the side where the distance between the first piston 25 and the second piston 26 increases is described as the forward rotation direction of the electric motor 21. Also, the rotational direction of the electric motor 21 on the side where the distance between the first piston 25 and the second piston 26 decreases is described as the reverse rotation direction of the electric motor 21. The controller 22 controls the braking force of the wheel in the service brake according to the operation of the driver's brake pedal by controlling the torque in the forward rotation direction generated by the electric motor 21.

[0020] <Configuration and Operation of EPB Mechanism 43> Furthermore, the drive unit 20 includes an EPB (electric parking brake) mechanism 43. The EPB mechanism 43 has an electromagnetic solenoid 44 assembled to the housing 23 and a ratchet gear 45 disposed inside the housing 23. The ratchet gear 45 is connected to the rotary shaft 29 of the electric motor 21 so as to rotate integrally.

[0021] The EPB mechanism 43 also includes a pawl member 46 that, together with the ratchet gear 45, constitutes a one-way clutch. The pawl member 46 meshes with the ratchet gear 45 in response to energization of the electromagnetic solenoid 44. When the pawl member 46 meshes with the ratchet gear 45, forward rotation of the electric motor 21 is permitted but reverse rotation is prohibited. The engagement of the pawl member 46 with the ratchet gear 45 is released by rotating the electric motor 21 in the forward direction while the electromagnetic solenoid 44 is de-energized. To activate the parking brake, the controller 22 rotates the electric motor 21 in the forward direction to generate a braking force on the wheels, and then energizes the electromagnetic solenoid 44 to mesh the pawl member 46 with the ratchet gear 45. As a result, the braking force applied to the wheels is maintained even when the electric motor 21 and the electromagnetic solenoid 44 are de-energized. On the other hand, the controller 22 releases the parking brake by rotating the electric motor 21 in the forward direction while the electromagnetic solenoid 44 is not energized.

[0022] <Assembly of backing plate 12 parts> In the electric braking device 10 of this embodiment, the backing plate 12 is composed of a plate main body 40 that forms a portion of the backing plate 12, and a sub-plate 39 that forms the remaining portion of the backing plate 12. As shown in FIG. 3 , a cutout portion 41 is formed in the plate main body 40. The cutout portion 41 corresponds to a rectangular cutout portion of the outer periphery of the disk-shaped backing plate 12, including a portion where components of the drive unit 20, such as the wheel cylinder 14, are installed. The sub-plate 39 is attached to the plate main body 40 so as to cover the cutout portion 41. The sub-plate 39 attached to the plate main body 40 forms a portion of the outer periphery of the backing plate 12.

[0023] The boundary between the plate body 40 and the sub-plate 39 in the backing plate 12 is formed by three straight sides. Of these three straight sides, two straight sides excluding the straight side facing the arc portion that forms part of the outer periphery of the backing plate 12 are referred to as side sides. A slit 42 extending along the boundary with the plate body 40 is formed in the edge of the portion that forms the side side of the sub-plate 39. The groove width of the slit 42 is set to a size that allows the edge 41A of the portion that forms the side side of the plate body 40 to be inserted. In this embodiment, the groove width of the slit 42 is set to a size slightly narrower than the thickness of the plate body 40.

[0024] In this embodiment, the components of the drive unit 20 are assembled to the backing plate 12 in the following manner. First, the components of the drive unit 20 are assembled to the sub-plate 39. Specifically, first, the components of the drive unit 20 arranged inside the housing 23 are assembled inside the housing 23. Next, the housing 23 is fixed to the sub-plate 39 with a portion of the housing 23 inserted into an opening 39A formed in the sub-plate 39. The housing 23 is fixed to the sub-plate 39 by, for example, bolting. In this way, the wheel cylinder 14 arranged inside the housing 23 is assembled to the sub-plate 39. Next, the electric motor 21 and the electromagnetic solenoid 44 are fixed to the housing 23. In this way, the wheel cylinder 14 and the electric motor 21 are assembled to the sub-plate 39 with the sub-plate 39 positioned between the wheel cylinder 14 and the electric motor 21. Note that the electric motor 21 and the controller 22 may also be fixed to the sub-plate 39. In this embodiment, the process of assembling the components of the drive unit 20 to the sub-plate 39 corresponds to the first process.

[0025] 3 and 4, the sub-plate 39 to which the components of the drive unit 20 are assembled is fixed to the plate body 40. Specifically, the edge 41A of the cutout 41 is inserted into the slit 42, and the sub-plate 39 is inserted into the cutout 41 of the plate body 40 from the radially outer side thereof. The edge 41A of the plate body 40 serves as a guide when assembling the sub-plate 39 to the plate body 40.

[0026] As described above, the slits 42 are formed to have a width slightly narrower than the thickness of the plate body 40. The edge portions 41A are thick enough to be press-fitted into the slits 42. By inserting the edge portions 41A into the slits 42, the plate body 40 and the sub-plate 39 are fixed together.

[0027] In addition, in the backing plate 12 to which the components of the drive unit 20 are thus assembled, the sub-plate 39 can be separated from the plate body 40 while the components of the drive unit 20 remain assembled together. In this embodiment, the process of fixing the sub-plate 39 to the plate body 40 corresponds to the second process.

[0028] <Effects of the First Embodiment> In the above embodiment, the wheel cylinder 14 and the electric motor 21 are pre-assembled on the sub-plate 39, which is fixed to the plate body 40, so that the wheel cylinder 14 and the electric motor 21 are respectively assembled to different surfaces of the backing plate 12. This eliminates the need to individually fix the wheel cylinder 14 and the electric motor 21 to different surfaces of the backing plate 12, which is large and difficult to handle. This improves the workability of assembling parts to the backing plate 12 during manufacturing.

[0029] When the sub-plate 39 is fixed to the plate body 40 by fastening bolts or the like, a fastening tool is required. However, the sub-plate 39 is fixed to the plate body 40 by inserting the edge portion 41A of the plate body 40 into the slit 42 formed in the sub-plate 39. Therefore, it is possible to assemble the components of the drive unit 20 to the backing plate 12 without using a tool.

[0030] An opening for passing the rotating shaft 29 is formed in the housing 23 at the connection portion of the electric motor 21. When the electric motor 21 is assembled to the housing 23 after the housing 23 is assembled to the backing plate 12, as in the case of Patent Document 1, the opening of the housing 23 remains open to the outside until the assembly of the electric motor 21 is completed. This makes it easier for foreign matter to enter the housing 23. In contrast, in this embodiment, the electric motor 21 is assembled to the housing 23 in advance, and then the assembly work to the backing plate 12 is performed. The assembly of parts to the sub-plate 39 can be performed in a smaller work space than the assembly of parts to the backing plate 12. Meanwhile, the smaller the work space, the easier it is to maintain cleanliness. Therefore, this embodiment prevents foreign matter from entering the housing 23.

[0031] In this embodiment, the front surface of the sub-plate 39 corresponds to the first surface of the sub-plate 39 to which the wheel cylinder 14 is attached, and the back surface of the sub-plate 39 corresponds to the second surface of the sub-plate 39. In this embodiment, the front surface of the plate body 40 corresponds to the first surface of the plate body 40, which is the surface on which the wheel cylinder 14 is located when the sub-plate 39 is fixed. Furthermore, the back surface of the plate body 40 corresponds to the second surface of the plate body 40, which is the back side of the first surface.

[0032] (Second embodiment) Next, a second embodiment of an electric braking device and a manufacturing method thereof will be described in detail with reference to Figures 5 to 7. In this embodiment, components common to the above embodiment will be assigned the same reference numerals and detailed description thereof will be omitted.

[0033] In this embodiment as well, the backing plate 12 is divided into a sub-plate 50 and a plate body 51. The components of the drive unit 20 are integrally assembled to the sub-plate 39. The drive unit 20 has the same configuration as that of the first embodiment.

[0034] As shown in Fig. 5, an opening 52 is formed in the plate body 51 in this embodiment. The area where the opening 52 is formed includes a portion of the backing plate 12 where the wheel cylinder 14 is installed. Note that the outline of the wheel cylinder 14 is indicated by a two-dot chain line inside the opening 52 in Fig. 5. The opening 52 is formed in a shape and dimensions that allow the wheel cylinder 14 to pass through. In addition, a through hole 55 is formed in the portion of the plate body 51 surrounding the opening 52.

[0035] Fig. 6 shows the planar structure of the sub-plate 50 with the components of the drive unit 20 assembled thereto. In Fig. 6, the outline of the opening 52 formed in the plate body 51 is indicated by a two-dot chain line. The sub-plate 50 is formed to have a size slightly larger than the opening 52. A threaded hole 53 is formed in the sub-plate 50 in the vicinity of the position where the wheel cylinder 14 is to be assembled. The threaded hole 53 is formed in a position that will overlap with the through-hole 55 of the plate body 51 when the sub-plate 50 is fixed to the plate body 51.

[0036] In this embodiment as well, when assembling the components of the drive unit 20 to the backing plate 12, a first step is performed in which the components of the drive unit 20 are assembled to the sub-plate 50. Then, a second step is performed in which the sub-plate 50, to which the components of the drive unit 20 have been assembled in the first step, is fixed to the plate main body 51, thereby assembling the components of the drive unit 20 to the backing plate 12.

[0037] FIG. 7 shows the state of the work of fixing the subplate 50 to the plate body 51 in the second step. In the fixing work, first, the wheel cylinder 14 assembled to the subplate 50 is passed through the opening 52 from the back side of the plate body 51. Then, with the subplate 50 in contact with the back surface of the plate body 51, the bolt 54 is fastened from the front side of the plate body 51 through the through hole 55 and into the threaded hole 53, thereby fixing the subplate 50 to the plate body 51. In this way, the subplate 50 is fixed to the plate body 51 so that the back surface of the plate body 51 covers the opening 52 and its periphery. When the bolt 54 is removed from the threaded hole 53 and the subplate 39 is released from the plate body 51, it can be separated from the plate body 51 while the wheel cylinder 14 and the electric motor 21 remain integrally assembled.

[0038] In this embodiment, too, there is no need to separately fix the wheel cylinder 14 and the electric motor 21 to different surfaces of the backing plate 12. This improves the workability of assembling parts to the backing plate 12 during manufacturing. Furthermore, because the electric motor 21 is assembled to the housing 23 in advance and then the sub-plate 50 is fixed to the plate body 51, the intrusion of foreign matter into the housing 23 is suppressed.

[0039] In this embodiment, the front surface of the sub-plate 50 corresponds to the first surface of the sub-plate 50 to which the wheel cylinder 14 is attached, and the back surface of the sub-plate 50 corresponds to the second surface of the sub-plate 50. In this embodiment, the front surface of the plate body 51 corresponds to the first surface of the plate body 51, which is the surface on which the wheel cylinder 14 is located when the sub-plate 50 is fixed. Furthermore, the back surface of the plate body 51 corresponds to the second surface of the plate body 51, which is the back side of the first surface.

[0040] (Other embodiments) The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0041] In the first embodiment, the sub-plate 39 is fixed to the plate body 40 by inserting the edge 41A into the slit 42, but it may be fixed by other methods such as bolt fastening. Also, in the second embodiment, the sub-plate 50 may be fixed to the plate body 51 by a method other than bolt fastening.

[0042] The sub-plates 39 and 50 may be integrated into the housing 23. The housing 23 may be divided into a portion that constitutes the wheel cylinder 14 and a portion that accommodates the first small diameter gear 30, the first large diameter gear 31, the second small diameter gear 32, and the ratchet gear 45.

[0043] If the drive unit 20 does not have a parking brake function, the EPB mechanism 43 may be omitted. The drive unit 20 may be configured to operate only as a parking brake, not as a service brake. In this case, brake fluid may be introduced into the cylinder 24 to configure the wheel cylinder 14 to operate hydraulically, or a wet wheel cylinder that operates hydraulically may be added to operate the service brake hydraulically.

[0044] In the first embodiment, the shape of the cutout portion 41 does not have to be rectangular. For example, the boundary between the plate main body 40 and the sub-plate 39 may have a rounded shape where the three straight sides connect to one another. Specifically, of the three straight sides, the straight side facing the arc portion that forms part of the outer periphery of the backing plate 12 and the two side sides may be connected in an arc shape rather than at a right angle. Furthermore, the boundary between the plate main body 40 and the sub-plate 39 may be fan-shaped, having one arc shape, instead of three sides. In this case, the shape of the sub-plate 39 may also be fan-shaped.

[0045] Although the sub-plate 39 was attached to the plate body 40 by press-fitting the edge portion 41A into the slit 42, the attachment method is not limited to this. For example, a liquid sealing material may be applied in advance to at least one of the inside of the slit 42 and the edge portion 41A, and then the edge portion 41A may be inserted into the slit 42. In this case, the sealing material may be a material that hardens over time. Also, in this case, the thickness of the slit 42 and the thickness of the edge portion 41A may be approximately the same. In other words, the thickness of the slit 42 and the thickness of the edge portion 41A may be such that the edge portion 41A can be inserted into the slit 42 without being press-fitted.

[0046] In the sub-plate 39, the slits 42 may be formed not only in the portions corresponding to the side edges, but also in the portions corresponding to the edges extending in a direction perpendicular to the two side edges. The thickness of the slit 42 does not have to be constant in the longitudinal direction of the slit 42. For example, the slit 42 may be formed so that the thickness of the slit 42 decreases toward the radially outer side of the backing plate 12. In this case, the sub-plate 39 begins to be gradually press-fit as it is inserted into the plate body 40. This makes it easier to insert initially. Furthermore, the plate body 40 may be configured so that the thickness of the edge portion 41A decreases toward the radially outer side. In this case, the width of the slit 42 may be constant in the longitudinal direction.

[0047] The width of the slit 42 may not be constant in the longitudinal direction of the slit 42. The width direction corresponds to the left-right direction in FIG. 3. For example, the width of the slit 42 may narrow toward the radially outer side of the backing plate 12. In this case, the width of the slit 42 is wider closer to the center of the backing plate 12, making it easier to insert the sub-plate 39 into the plate body 40 at the initial stage of insertion.

[0048] The sub-plate 39 and the plate body 40 may each have a plurality of concave-convex shapes formed at the portion where the slit 42 and the edge 41A come into contact with each other. When the sub-plate 39 is inserted into the plate body 40, the sub-plate 39 and the plate body 40 may rub against each other, potentially generating debris. Even in this case, it is possible for debris to accumulate in the gaps between adjacent concave-convex shapes.

[0049] Although the slits 42 are formed directly in the sub-plate 39, this is not limitative. For example, a member having a slit corresponding to the slit 42 may be attached to a sub-plate 39 that does not have the slit 42 formed therein. [Explanation of symbols]

[0050] 10…Electric braking device 11...Brake drum 12...Backing plate 13...Axle hole 14...Wheel cylinder 15...Anchor member 16, 17...Brake shoes 18...Friction material 19...Return spring 20...Drive unit 21...Electric motor 22...Controller 23…Housing 24...Cylinder 25...First piston 26...Second piston 27, 28...Pressing part 29...Rotation axis 30...First small diameter gear 31...First large diameter gear 32...Second small diameter gear 33...Second large diameter gear 34...Internal spline 35...Screw shaft 36...External spline 37...Male thread 38...Internal thread 39, 50...Subplate 39A…Opening 40, 51...Plate body 41...Notch 41A…Edge 42...Slit 43…EPB mechanism 44...Electromagnetic solenoid 45...Ratchet gear 46...Claw member 52...Aperture 53...Screw hole 54...Bolt 55...Through hole

Claims

1. A drum-type electric braking device in which a wheel cylinder and an electric actuator are respectively mounted on a backing plate, and the electric actuator drives the wheel cylinder to generate a braking force on a wheel, The backing plate is configured by assembling a sub-plate that constitutes the remaining part of the backing plate to a plate body that constitutes a part of the backing plate, The wheel cylinder is attached to a first surface side of the sub-plate, and the electric actuator is attached to a second surface side that is a reverse side of the first surface side, the sub-plate includes an outer periphery of the backing plate, An edge portion of the plate body, which is a boundary portion between the sub-plate and the plate body, is inserted into a slit formed in the sub-plate along the boundary portion between the sub-plate and the plate body. Electric braking device.

2. A drum-type electric braking device in which a wheel cylinder and an electric actuator are respectively mounted on a backing plate, and the electric actuator drives the wheel cylinder to generate a braking force on a wheel, The backing plate is configured by assembling a sub-plate that constitutes the remaining part of the backing plate to a plate body that constitutes a part of the backing plate, The wheel cylinder is attached to a first surface side of the sub-plate, and the electric actuator is attached to a second surface side that is a reverse side of the first surface side, In the plate body, when the sub-plate is fixed, the surface on which the wheel cylinder is located is defined as a first surface of the plate body, and the other surface is defined as a second surface of the plate body. The plate body has an opening through which the wheel cylinder can pass, The sub-plate is attached to the second surface of the plate body in a state where it covers the opening. Electric braking device.

3. A method for manufacturing a drum-type electric braking device comprising a wheel cylinder and an electric actuator, each of which is mounted on a backing plate, and in which the electric actuator drives the wheel cylinder to generate a braking force on a wheel, comprising: a sub-plate constituting a part of the backing plate includes an outer periphery of the backing plate, a first step including a step of assembling the wheel cylinder to a first surface side of the sub-plate, and a step of assembling the electric actuator to a second surface side that is a reverse side of the first surface; a second step of assembling the sub-plate, to which the wheel cylinder and the electric actuator have been assembled in the first step, to a plate body constituting the remaining portion of the backing plate; Including, In the second step, the subplate is assembled to the plate body by inserting an edge portion of the plate body, which is a boundary portion between the subplate and the plate body, into a slit formed in the subplate along the boundary portion between the subplate and the plate body. A method for manufacturing an electric braking device.

4. A method for manufacturing a drum-type electric braking device comprising a wheel cylinder and an electric actuator, each of which is mounted on a backing plate, and in which the electric actuator drives the wheel cylinder to generate a braking force on a wheel, comprising: a first step including a step of assembling the wheel cylinder to a first surface side of a sub-plate constituting a part of the backing plate, and a step of assembling the electric actuator to a second surface side which is a reverse side of the first surface; a second step of assembling the sub-plate, to which the wheel cylinder and the electric actuator have been assembled in the first step, to a plate body constituting the remaining portion of the backing plate; Including, In the plate body, when the sub-plate is fixed, the surface on which the wheel cylinder is located is defined as a first surface of the plate body, and the other surface is defined as a second surface of the plate body. the plate body has an opening formed therein through which the wheel cylinder can pass, In the second step, the wheel cylinder is passed through the opening from the second surface side of the plate body, and the sub-plate is attached to the second surface of the plate body so as to cover the opening while the sub-plate is in contact with the second surface of the plate body. A method for manufacturing an electric braking device.

Images